JP4067477B2 - Method for decomposing resin components - Google Patents

Description

  The present invention relates to a method for decomposing a resin component, and more particularly to a method for decomposing plastic-containing waste by dissolving waste plastics mixed in industrial waste from the waste.

  Industrial waste is a state in which many types of materials such as resin, metal, glass, earth and sand, wood chips, and oil are mixed, and from the viewpoint of cost and labor, it is a simple process that relies on landfill without separation. The method was mainstream. However, with the recent strengthening of landfill regulations, it has become difficult to rely on the landfill disposal method unconditionally when processing industrial waste. Recently, with the increasing awareness of recycling, landfill disposal in which undegraded resin components that are mainly raw materials that are difficult to decompose are buried in the ground is regarded as a problem, and a new treatment method is desired. Has been. For this reason, the current mainstream is shifting to a method of incineration after passing through a plurality of processing stages.

  This situation is exactly the same for the treatment of the resin component in the waste vehicle body. For this reason, when processing resin components, waste oil components obtained by steam-decomposing wastes from scrap cars after pulverizing the resin-concentrated parts in scrap cars, decomposition residues when solids are decomposed by catalytic action, etc. It is a common treatment method to complete the treatment by incineration.

  However, incineration in the above-mentioned process may generate harmful chlorine gas originating from the vinyl chloride resin in the residue. If left untreated, it can develop into a dioxin problem. There is also sex. Therefore, it is ideal if the resin component can be separated and separated in the process of producing the residue, but the pulverized dust containing many resin-concentrated parts is usually heat insulating material, wood chips, glass pieces and harnesses, polyvinyl chloride coated wire, Only a resin component cannot be separated unless a removal operation corresponding to each type of the contaminants is obtained in a state where many types of soil and sand are mixed in a complicated manner. In addition, in order to add functionality such as heat resistance and oil resistance, the component composition is often complicated by using an additive in the resin component or performing a surface treatment. For this reason, in order to isolate | separate only resin, many procedures must be passed, and the above incineration disposal is actually performed, without reaching the complete separation of a resin component. As a result, it cannot be denied that measures against generated chlorine gas remain insufficient.

Conventionally, what was shown in patent document 1 as what took this kind of chlorine gas countermeasure is known. In this method, after the hydrocarbon-based plastic is selectively dissolved in the previous dissolution fractionation step, the hydrogen chloride-based gas is removed by performing a thermal decomposition step on the different hydrocarbon-based plastic such as vinyl chloride.
Japanese Patent Laid-Open No. 11-310659 (page 4, FIGS. 1 and 2)

  By the way, the above thermal decomposition process is based on the melt dechlorination treatment, and there are many situations that target gaseous substances such as generated hydrogen chloride gas and gas phase reaction at the time of thermal decomposition. Management is required. In general, if there is a process involving a gas phase reaction, it is inevitable that the burden on management and equipment becomes large.

  In view of the above-described problems, an object of the present invention is to provide a method capable of reliably separating resin components in industrial waste, in particular, waste originating from scrap cars, with a simpler process.

In order to solve the above problems, the present invention provides at least one solvent selected from waste gasoline, waste light oil, waste kerosene, thinner, benzene, hexane, and acetone as a weakly polar or nonpolar solvent , and N as a strongly polar solvent. -Plastic- containing waste in a mixed solution consisting of one solvent selected from methylpyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, γ-butyrolactone, diacetone alcohol, methyl isobutyl ketone, methyl ethyl ketone, ethylbenzene and 2-pyrrolidone. After the immersion, the mixed solution is heated, or the mixed solution composed of the weak polar or nonpolar solvent and the strong polar solvent is heated, and then the plastic-containing waste is put into the mixed solution. In addition, containing heated plastic Against immersion mixed solution of wastes, it is characterized by contacting the decomposition reaction with water vapor.

  According to these, the hydrocarbon-based plastic in the plastic-containing waste and the different hydrocarbon-based plastic represented by vinyl chloride are dissolved in the weakly polar / nonpolar solvent and the strongly polar solvent, respectively. At this time, the chlorine content of the vinyl chloride dissolved in the strong polar solvent increases the acidity of the whole solvent and promotes the dissolution of other undissolved resin components. Further, by performing the heat treatment, the evaporation of the solvent proceeds and the acidity of the solvent further increases, so that further dissolution of the undissolved resin component can be obtained. As a result, the largest vinyl chloride resin to be captured can be recovered in a state dissolved in a solvent, that is, in a state decomposed in a liquid phase process that is relatively easy to operate, and the transition to subsequent processing is facilitated.

  In this case, the heating temperature range is desirably 80 to 250 ° C. This temperature range is near the molding temperature of the resin used, and the resin component is easily changed to a molten state, which is advantageous for promoting dissolution. On the other hand, if it is less than 80 ° C., it takes a long time to obtain molecular cutting energy for the constituent molecules of the resin component, and the efficiency is poor. There is concern that it will become intense. Furthermore, by setting it as 250 degrees C or less, there also exists an effect that the approach to dioxin generation temperature (400-650 degreeC) can be avoided with sufficient margin.

  Furthermore, non-polar solvents include waste gasoline, waste light oil, waste kerosene, thinner, benzene, hexane, etc., weak polar solvents such as acetone, and strong polar solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran Γ-butyrolactone, diacetone alcohol, methyl isobutyl ketone, methyl ethyl ketone, ethylbenzene, 2-pyrrolidone, and the like can be used. In addition, as a weakly polar or nonpolar solvent, you may use the mixture which used multiple above-mentioned solvent substances.

 The resin component dissolved in this way may be recovered together with the solution from which it has been eluted, and then proceeded to a separation process, but after the catalytic decomposition reaction with water vapor in the state of the above-mentioned immersion mixed solution of plastic-containing waste. It is good also as what performs a process. This is because in the state of the heated immersion solution, a substantial part of the resin component has already eluted in the solution, and it is considered that the catalytic decomposition reaction with water vapor proceeds efficiently. Under the present circumstances, the resin component which contacted water vapor | steam will be decomposed | disassembled, the coupling | bonding between the carbon atoms in the hydrocarbon compound which comprises this will be cut | disconnected.

  The catalytic cracking reaction with water vapor is carried out under reaction conditions of a water vapor partial pressure of 0.01 to 0.3 atm with respect to a total pressure of 1.01 to 1.3 atm, and a water vapor temperature of 300 ° C. or lower. Can be done.

  As a result, a hydration reaction of water vapor with respect to the hydrocarbon compound constituting the resin component occurs under almost normal pressure conditions and even at a water vapor temperature of 300 ° C. or lower, and thus the necessary catalytic cracking reaction can be performed. . For this reason, it is possible to reduce the apparatus configuration in terms of the degree of pressure resistance. And since this temperature range is certainly less than the dioxin generation temperature (about 400-650 degreeC), resin component decomposition | disassembly can be advanced on safe conditions.

  According to the method of the present invention, hydrocarbon-based plastics in plastic-containing waste and different hydrocarbon-based plastics such as vinyl chloride are dissolved in a mixed solvent, and are obtained not as a solid residue but as a dissolved product in the mixed solvent. So it can be handled in solution. That is, the resin component can be separated and decomposed easily and reliably by the dissolving operation. Thereby, while being able to simplify the apparatus structure and management at the time of operation, transfer to subsequent processes, such as chlorine gas recovery, becomes easy.

  Further, by blowing water vapor into the immersion solution, it is possible to cause a catalytic decomposition reaction to further decompose the resin component. The reaction conditions at this time may be mild, and no special complication of the apparatus configuration is necessary.

  FIG. 1 is a schematic view of an apparatus for dissolving and decomposing a resin component when using the dissolving method of the present invention. The container 1 of this apparatus is a shape which can store the solution 2 in the center bottom part, and can extract the solution 2 with the drain valve 3 provided in the deepest part. In addition, openings 4, 5, 6, and 7 are provided in the upper portion of the container 1, and function as an inlet 4, a central distillation port 5, a delivery port 6, and a reactant outlet 7, respectively. Further, the rotating shaft core 8 penetrates the bottom 1 a of the container 1 from the outside, and a plurality of cutting blades 9 supported by the rotating shaft 8 are provided at positions where the rotating shaft 8 is immersed in the storage portion of the solution 2. The rotating shaft 8 is connected to a driving motor 11 by a belt 10 outside the container 1, and the cutting blade 9 rotates in the solution 2 when the rotating shaft 8 rotates by this driving.

  And along the bottom wall surface which pinched | interposed the deepest lowest part 1a of the container 1 in which this cutting blade 9 was provided, the carrying-in conveyor 12 was provided in the inlet 4 side, and the carrying-out conveyor 13 was provided in the sending exit 6 side. In addition, 4a, 5a, 6a in FIG. 1 shows the distiller mounted in the insertion port 4, the central distillation port 5, and the delivery port 6, and the reaction material outlet 7 is provided with the shutter 7a.

  When the resin component in the ASR which is a plastic-containing waste is dissolved using the apparatus of FIG. 1, a mixed solution 2 composed of a weakly polar or nonpolar solvent and a strongly polar solvent is injected into the container 1 in advance. Then, ASR (plastic-containing waste) pulverized to an appropriate size suitable for treatment from the charging port 4 is continuously charged into the solution 2 and immersed therein. Thereafter, heating is performed by a heating means (not shown) attached to the container 1.

  When the waste is introduced from the inlet 4, the distiller 4 a is operated, and the vapor from the mixed solution 21 is exposed to the plastic waste, so that the plastic component is softened, and the subsequent melting and the rotary cutting blade 9 are used. Cutting and miniaturization are easy. Further, by using the carry-in conveyor 12 at the time of charging, the immersion in the solution 2 is performed smoothly.

  Note that the mixed solution 2 can be used as non-polar solvents such as waste gasoline, waste light oil, waste kerosene, thinner, benzene, hexane, etc., weak polar solvents such as acetone, and strong polar solvents such as N -Methylpyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, γ-butyrolactone, diacetone alcohol, methyl isobutyl ketone, methyl ethyl ketone, ethylbenzene, and 2-pyrrolidone. As the weakly polar or nonpolar solvent, a mixture using a plurality of the above solvent substances may be used.

  As for the heating conditions at the time of heating with respect to the mixed solution 2 which immersed the plastic waste fragmented as mentioned above, it is desirable that it is 80-250 degreeC. By this heating, the hydrocarbon-based plastic in the plastic-containing waste and the different hydrocarbon-based plastic typified by vinyl chloride are dissolved in the weakly polar / nonpolar solvent and the strongly polar solvent, respectively. Examples of such plastic materials include BR, SBR, natural rubber, PVC, and acrylic resin.

  And water vapor | steam is blown with respect to the solution 2 with the water vapor | steam introduction pipe | tube outside a figure, performing the heating in this temperature range. The temperature and partial pressure of the water vapor at this time are 110 ° C. and 0.15 atm (total pressure 1.15 atm), respectively. Then, the resin component eluted in the solution 2 comes into contact with water vapor and is decomposed by a hydration reaction therewith. Further, the hydrocarbon components originating from the decomposed resin components can be removed by distillation using the distillers 5a and 6a, and the dissolved amount of the resin components newly supplied as waste pieces can be secured. At this time, the chloride-derived chlorine content in the resin elutes as chloride ions in the strong polar solvent and remains in the solution 2 without being distilled. Therefore, as the volume of the distilled solvent decreases, the chloride ion concentration in the solution increases and the acidity increases. This also contributes to an increase in the dissolving power for waste pieces.

  Further, at the time of this heating, the rotating shaft 8 is rotated via the belt 10 by the drive motor 11 and the cutting blade 9 is rotated. As a result, the pulverization of the waste pieces further proceeds, and the mixed solution 2 is agitated to promote the dissolution, decomposition and distillation of the waste pieces.

  Through such a process, the plastic-containing waste thrown into the solution 2 has a hydrocarbon-based plastic resin component dissolved in a weakly polar / non-polar solvent, and a different hydrocarbon-based plastic resin component represented by vinyl chloride. Is dissolved in a strong polar solvent, and in this state, catalytic cracking reaction with water vapor is carried out. As a result, it is divided into those that are decomposed and distilled and removed to the outside, those that remain dissolved in the solution 2, and those that become sludge residue. Chlorine ions are dissolved in the solution 2, and may be recovered and separated by opening and closing the drain valve 3 in the dissolved state and transferred to the next processing step. Further, the sludge-like residue is extracted from the solution 2 by the carry-out conveyor 13 to be transferred to the next processing step. Since the chlorine component is removed from the residue, the risk of generation of harmful chlorine gas and dioxin gas resulting from the combustion is minimized.

  In this embodiment, the plastic-containing waste is immersed in a mixed solution composed of a strong solvent, and then the mixed solution is heated. However, the mixed solution composed of a weakly polar or nonpolar solvent and a strong solvent. It is good also as a method of throwing a plastic containing waste in this mixed solution after heating.

  Waste gasoline is used as a nonpolar solvent, and a mixed solvent is composed of this waste gasoline and a polar solvent at a ratio of 1/3 by weight, and further, a shredder dust at a ratio of 1/4 by weight with respect to this mixed solution. (Containing 65% resin component) was charged into the apparatus shown in FIG. When the heating temperature at this time was changed, it was found that the treatment temperature and the dissolved amount of the resin component showed a correlation as shown by the solid line in FIG.

[Comparative Example 1]
When the resin component in the shredder dust was dissolved in the same manner as in [Example 1] except that kerosene as a non-polar solvent was used instead of the mixed solution, the amount of dissolution was as shown by the dotted line in FIG. It remained low.

  From comparison of these results, it can be seen that mixing of a polar solvent is effective in improving the amount of resin component dissolved.

  The ratio of the mixed solvent and the shredder dust also affects the amount of dissolution in the shredder dust. FIG. 3 shows various amounts of mixed solvent / shredder dust weight ratio (corresponding to the solvent ratio in FIG. 3) with respect to the amount dissolved when heating temperature is kept constant at 160 ° C. for 1 hour. The correlation with the amount of dissolution is shown.

  Acetone is used as a weak polar solvent, and a mixed solvent is composed of this acetone and a polar solvent in a predetermined weight ratio. Further, a PVC resin is added to the mixed solution in the apparatus shown in FIG. Heated.

At this time, the dissolution amount correlation when the acetone / polar solvent ratio is changed as follows is shown as follows.
Acetone / polar solvent ratio = 70: 30... FIG.
Acetone / polar solvent ratio = 80: 20... FIG.
Acetone / polar solvent ratio = 90: 10... FIG.
4 to 6, it can be seen that the amount of the PVC resin dissolved does not significantly depend on the ratio of the polar solvent, but rather is dissolved reliably only by the presence of the polar solvent.

  Among various polar solvents (N-methyl-2-pyrrolidone, dimethylformamide, γ-butyrolactone, butyl benzoate, ethylbenzene, 2-pyrrolidone), N-methyl-2-pyrrolidone is effective in dissolving PVC resin. You can see that

  Using thinner as the nonpolar solvent and N-methyl-2-pyrrolidone as the polar solvent, a mixed solution with a weight ratio of thinner and N-methyl-2-pyrrolidone of 80:20 is prepared. When 12 kg of the resin component was put into the apparatus of FIG. 1 storing 30 kg of this mixed solution and heated at 150 ° C. for 2 hours, 14 kg of sludge residue and 28 kg of solution were obtained, and the resin component was dissolved. I understand.

  Using kerosene as the nonpolar solvent and dimethylformamide as the polar solvent, a mixed solution having a weight ratio of kerosene and dimethylformamide of 80:20 is prepared. When 20 kg of the resin component was put into the apparatus of FIG. 1 storing 40 kg of this mixed solution and heated at 170 ° C. for 90 minutes, 22 kg of sludge residue and 38 kg of solution were obtained, and the resin component was dissolved. I understand.

  It can be seen that by making the heating time longer than the initial 90 minutes, a decrease in the weight of the residue and an increase in the amount of the solution are observed, and the amount of the resin component dissolved increases.

  When steam was introduced into the sludge residue under the conditions of 160 ° C. and 0.15 L / min., A residue of about 6 kg was obtained. When this residue was heated and then volatile components were removed, 5.5 kg of an elastic material was obtained. As shown in FIGS. 7 and 8, the elastic strength of this elastic body is found to depend on the steam blowing speed and temperature used for distillation. By setting these conditions and controlling the elastic strength, it is possible to reuse the obtained residue as a sound absorbing material or an impact absorbing material.

  INDUSTRIAL APPLICABILITY The present invention can be used for preventing generation of harmful chlorine gas and dioxin caused by resin components in shredder dust. In particular, it can be used as an important process for improving the processing efficiency by positioning it as a pretreatment method for separating the resin component in the waste treatment method including a resin component such as waste plastic.

Resin component dissolution and decomposition equipment Graph showing the correlation between heating temperature and amount of dissolution A graph showing the correlation between the ratio of the weakly polar or nonpolar solvent to the strongly polar solvent and the amount dissolved. A graph showing the correlation between dissolution time and dissolution amount (weakly polar solvent: strongly polar solvent = 70: 30) A graph showing the correlation between dissolution time and dissolution amount (weakly polar solvent: strongly polar solvent = 80: 20) Graph showing the correlation between dissolution time and dissolution amount (weak polar solvent: strong polar solvent = 90: 10) Graph showing the correlation between the elastic strength of the elastic material obtained by steam distillation of the residue and the blowing speed Graph showing the correlation between the elastic strength of the elastic material obtained by steam distillation of the residue and the distillation temperature

Explanation of symbols

1 reaction vessel 2 mixed solution

Claims (4)

At least one solvent selected from waste gasoline, waste light oil, waste kerosene, thinner, benzene, hexane and acetone as weakly polar or nonpolar solvent, and N-methylpyrrolidone, dimethylformamide, dimethylacetamide as strong polar solvents After immersing the plastic-containing waste in a mixed solution consisting of one solvent selected from tetrahydrofuran, γ-butyrolactone, diacetone alcohol, methyl isobutyl ketone, methyl ethyl ketone, ethylbenzene and 2-pyrrolidone , A method for decomposing a resin component, comprising heating and subjecting the heated mixed solution of plastic-containing waste to a catalytic decomposition reaction with water vapor . At least one solvent selected from waste gasoline, waste light oil, waste kerosene, thinner, benzene, hexane and acetone as weakly polar or nonpolar solvent, and N-methylpyrrolidone, dimethylformamide, dimethylacetamide as strong polar solvents , Tetrahydrofuran, γ-butyrolactone, diacetone alcohol, methyl isobutyl ketone, methyl ethyl ketone, ethylbenzene and 2-pyrrolidone, a mixed solution is heated, and then the plastic-containing waste is placed in the mixed solution. A method for decomposing a resin component, which comprises dipping and subjecting the heated mixed solution of plastic-containing waste to a catalytic decomposition reaction with water vapor .   The method for decomposing a resin component according to claim 1 or 2, wherein a heating temperature range of the mixed solution is 80 to 250 ° C. The catalytic cracking reaction with water vapor is performed under reaction conditions of a water vapor partial pressure of 0.01 to 0.3 atm with respect to a total pressure of 1.01 to 1.3 atm and a water vapor temperature of 300 ° C or less. Item 4. A method for decomposing a resin component according to any one of Items 1 to 3 .

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